1. Field of the Invention
This invention relates to recording and interpreting factors present in laundering a batch of commercial linens, and particularly to the inclusion of a dyed fabric swatch which records the chlorine bleach activity on the linens.
2. Description of the Related Art
Chlorine is the bleaching agent most commonly used in laundering fabrics such as those used in commercial linens.
Overbleaching reduces the useful life of textile products; it weakens them by damaging their fiber, and reduces their aesthetic appeal by facing or removing color. Overbleaching may occur in the commercial laundering process, as it is often difficult for management to insure that appropriate quantities of chlorine bleach are used in an individual laundry batch.
The amount of bleach included in a particular laundry solution may not, of itself, be a sufficient basis for concluding whether or not the optimum concentration of chlorine was used. Factors other than chlorine concentration may increase the extent of bleaching activity--for example, high temperature and incorrect pH of the laundry solution. On the other hand, excess soil (much of which might have been removed by pre-rinsing) may use up part of the chlorine activity present.
It is conventional to utilize test pieces in a laundry batch, the pieces having indicators attached for various purposes. Thus, the temperature of a laundry solution may be recorded by use of a temperature test strip. Wool, an animal fiber, may be destroyed by excessive alkalinity; hence it is known to attach a swatch of wool fabric onto a laundry test piece. The extent to which the wool swatch has been "eaten away" in laundering reflects the alkalinity of the laundry solution. The activity of part of the chlorine used in a laundry solution may be taken up by excessive soil, some of which might have been removed by pre-rinsing. The presence of such excess soil is detectable by its re-deposition on a clean white swatch to indicate soil re-deposition. A conventional "fluidity" test determines how much cotton fiber a single laundering has consumed by measuring the decrease in fiber content in a swatch of the same fabric as the laundry batch with which it was laundered.
According to Luechauer U.S. Pat. No. 3,094,373, change in hue of a single fabric test swatch may serve as a record of the chlorinity of a laundry solution. Luechauer accomplishes this by including in each laundry batch a swatch with a single dye, which dye will actually change its hue when the swatch is laundered in a chlorine-containing solution.